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Race Formation (race + formation)
Selected AbstractsRe-Thinking the ,Origins Debate': Race Formation and Political Formations in England's Chesapeake ColoniesJOURNAL OF HISTORICAL SOCIOLOGY, Issue 2 2002Chris Smaje The debate over the ,origins' of racism in colonial North America has been dominated by the view that racism was a consequence of the enslavement of African-origin labour, or alternatively that it was a prior , perhaps primordial , sentiment that shaped the process of enslavement. This paper offers an alternative reading of the evidence in suggesting that race formation can be understood in relation to the emergence of new forms of imagining political communities in early modern England, and Europe more generally. This argument can not only help refine understanding of race formation in early colonial America, but also sociological theories of race more generally, while helping avoid some of the theoretical problems entailed in attempting to trace the ,origins' of social phenomena. [source] Recent evolution of host-associated divergence in the seabird tick Ixodes uriaeMOLECULAR ECOLOGY, Issue 21 2009FLORENT KEMPF Abstract Ecological interactions are an important source of rapid evolutionary change and thus may generate a significant portion of novel biodiversity. Such changes may be particularly prevalent in parasites, where hosts can induce strong selection for adaptation. To understand the relative frequency at which host-associated divergences occur, it is essential to examine the evolutionary history of the divergence process, particularly when it is occurring over large geographical scales where both geographical and host-associated isolation may playa part. In this study, we use population genetics and phylogeography to study the evolutionary history of host-associated divergence in the seabird tick Ixodes uriae (Acari, Ixodidae). We compare results from microsatellite markers that reflect more ecological timescales with a conserved mitochondrial gene (COIII) that reflects more ancient divergence events. Population structure based on microsatellites showed clear evidence of host-associated divergence in all colonies examined. However, isolated populations of the same host type did not always group together in overall analyses and the genetic differentiation among sympatric host races was highly variable. In contrast, little host or geographical structure was found for the mitochondrial gene fragment. These results suggest that host race formation in I. uriae is a recent phenomenon, that it may have occurred several times and that local interactions are at different points in the divergence process. Rapid divergence in I. uriae implies a strong interaction with its local host species, an interaction that will alter the ecological dynamics of the system and modify the epidemiological landscape of circulating micropathogens. [source] Evolution of intrinsic reproductive isolation among four North American populations of Rhagoletis pomonella (Diptera: Tephritidae)BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 1 2010JUAN RULL Across its range in North America, four geographically separated, ecologically and genetically diverged populations of hawthorn (Crataegus)-infesting Rhagoletis pomonella (Diptera: Tephritidae) flies inhabit the Eje Volcánico Trans Mexicano (EVTM), the Sierra Madre Oriental (SMO), the Chiapas Highlands (CHIS) and the USA. Here, we tested whether these four populations are reproductively isolated by any intrinsic, nonhost-related, pre- or postmating barriers to gene flow. Crossing experiments suggested that a low level of host-independent prezygotic isolation may exist between hawthorn flies from EVTM and the three other populations, but only with respect to a slight reduction in copulation duration in EVTM matings. Some evidence for postmating isolation was found, again primarily involving EVTM crossed to SMO, CHIS and US flies. Certain crosses produced no (SMO male × EVTM female) or few (EVTM male × CHIS female; CHIS male × SMO female) F1 hybrid offspring. F2 crosses were generally fertile, except for US male × CHIS female matings. Inherent reproductive isolation therefore appears to be quantitative rather than absolute between populations, as the possibility for gene flow exists through at least some combinations of mating among EVTM, SMO, CHIS and US flies. Our results are consistent with a recently advanced hypothesis that episodic introgression from Mexico into the USA has played a role in providing genetic variation, facilitating sympatric host race formation and the adaptive radiation of the R. pomonella sibling species' complex in the USA. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100, 213,223. [source] | ||||||||||